Is magnesium more reactive than carbon?

Magnesium is an alkaline earth metal and has two electrons in its valence shell that are easily given off to reactive species such as oxygen. Copper, however, has a different electron configuration. If you are familiar with orbitals, copper has a filled 3d orbital, which is the highest energy orbital. The unfilled orbital, 4s, is actually lower energy and will not be lost as easily since that would make the 3d orbital unfilled since one or two of those 3d electrons have to go down to fill the 4s orbital (thus Copper forms 1+ and 2+ ions). If I've completely lost you, the take-home message is that copper's reactive electron is not on its highest energy orbital and its highest energy orbital is filled. In contrast, the highest energy orbital is Magnesium is the same as its valence shell.